Optoelectric components or active optical devices such as diode lasers, light-emitting diodes (LEDs), and photodiode detectors are used for printing, data storage, optical data transmission and reception, laser pumps, and a multitude of other applications. Most optoelectric components are typically sealed inside a hermetically sealed package for performance requirements and operational stability. Optoelectric packages are intended to provide a hermetic structure to protect passive and active optical elements and devices as well as related electrical components from damage resulting from moisture, dirt, heat, radiation, and/or other sources.
For high-speed applications (e.g., 2 Gbps and above), proper operation of the optical and/or electrical components inside the package may be affected unless careful attention is paid to the packaging of these components. Standard optical module packaging such as that used in optical telecommunication applications requires a hermetic enclosure. Sealed packages are necessary to contain, protect, and electrically connect optoelectric components. These requirements have resulted in packages that are large, costly, and more difficult to manufacture than typical electronic packages. In fact, the cost and size of most optoelectric devices are mainly dominated by the package rather than the optical devices themselves.
Current designs of optoelectric packages and associated fabrication processes are not easily adapted for automated manufacturing techniques because conventional packages for optoelectric components such as large so-called “butterfly” packages are characterized by numerous mechanical parts (submounts, brackets, ferrules, etc.), and three-dimensional (3D) alignment requirements. Butterfly packages are basically can-and-cover type arrangements that contain an optical subassembly mounted to a metallic baseplate, with leads coming out of the sides for electrical connections. The optical subassembly may be built up separately, outside of the can, and then later installed in the can. The circuits within the optical subassembly are wire-bonded to the leads of the butterfly can, which is then sealed with a lid to create a hermetic enclosure. Unfortunately, conventional butterfly cans have a high profile, and are costly and time-consuming to manufacture. In addition, the electrical components require a separate electrical subassembly that is located outside of the butterfly can. The requirement of a separate electrical subassembly that is separate and apart from the optical subassembly inside the butterfly can increases manufacturing costs significantly.
Transistor-Outline (TO) packages are also commonly used to house optoelectric components. Conventional TO packages include a generally tall, cylindrical, u-shaped metal cap, and a metal header or base to which the metal cap is attached. In such packages, metal-based bonding techniques such as, for example, fusion welding, are often required to provide a hermetic seal between the metal cap and the header. To weld the metal cap onto the header, the header is typically formed of a metallic material such as Kovar™ or stainless steel. However, it is advantageous to use ceramic bases in connection with high-speed applications because ceramic bases are ideal for RF applications. Particularly, ceramic headers provide easy routing of high-speed circuits. Unfortunately, ceramic is not compatible with metal with regard to weldability, and therefore has not been widely used as the material for the header or base in conventional TO packages. In addition, because of the u-shaped configuration of the metal caps associated with conventional TO packages, expensive tooling such as, for example, two-piece tooling equipment, is required to manufacture the unshaped metal caps.
Typically, when active optical devices (e.g., diode lasers) and integrated circuits adapted to control the active optical devices (e.g., diode drivers) are spaced too far apart from each other, parasitic capacitance, resistance, and/or inductance may affect electrical signals traveling-between the components, thus resulting in slower signal propagation speeds. The electrical performance is of particular concern for high-speed applications. Consequently, electrical performance may be improved during high-speed applications when the distance between the active optical device and its associated driving or receiving integrated circuit chip is as short as possible. Although this arrangement may increase signal propagation speed, it may, unfortunately, also increase heat dissipation requirements of the assembly significantly.
As the power density increases in optoelectric devices and/or electrical components used in high-speed applications, an optimal heat sink is necessary to dissipate heat efficiently from the optoelectric device and/or electrical components. Heat sinks are devices capable of dissipating heat away from the optoelectric and/or electrical components into the surrounding atmosphere by convection. Typical heat sinks may include cooling fins attached to a heat sink base that is in contact with the header or base of the optoelectric package. The fins of the heat sink may have any shape and size necessary to dissipate heat away from the optoelectric device and/or electrical components, and may be oriented either parallel or perpendicular relative to the base of the optoelectric package.
Commercially available heat sinks are generally square or rectangular in shape. As such, the circular headers of conventional optoelectric packages require either modifications to the structural design of the heat sinks to be able to accommodate the circular headers, or manufacturing adjustments to attach the circular header to the square or rectangular heat sink. This configuration results in a complex, slow, and expensive manufacturing process. Additionally, the quality of the contact between the optoelectric package and the attached heat sink has a great impact on the overall thermal performance. Lower thermal impedance between the optoelectric package and the heat sink results in higher conductive heat transfer. Therefore, it is advantageous that the header of the optoelectric package be in intimate, conformal contact with the attached heat sink to optimize the thermal characteristics, which results in increased efficiency.
In addition, existing optoelectric packaging techniques often involve manual or semi-automated manufacturing processes. Therefore, to reduce manufacturing costs, it is advantageous to employ automated batch packaging processes that can fabricate a large number of optoelectric packages simultaneously.
Currently, there is a great demand for smaller optoelectric packages to allow for higher density of data transmission. Smaller optoelectric packages allow the devices (e.g., transceivers) into which the optoelectric packages are placed to become smaller. Moreover, optoelectric packages having a lower profile are advantageous due to space limitations of the devices into which the optoelectric packages are placed. Therefore, a need exists for an optoelectric package that provides for a more efficient use of limited space, allows for automated fabrication, and that is simple and inexpensive to fabricate.